Applying fundamental data to reduce the carbon dioxide footprint of aluminum smelters

Abstract

The aluminum smelting process is a strong emitter of CO2 with three major contributions: that arising from electrical energy generation and its utilization, the process conversion contribution linked with anode consumption and anode production, and the greenhouse gas equivalents of the intermittent perfluorocarbon (PFC) emissions. Fundamental studies of alumina solubility, the electrochemical mechanism for triggering the onset of PFC emissions, and the importance of both mixing and current density on the speed of termination of anode effects, help define better paths for process operation. In conjunction with advising prebake aluminum smelters on process optimization, the authors have successfully tested the differences in theory and practice, and applied fundamentals in the operating environment to change some of the installed control strategies, termination mechanisms, and work practices. These changes have improved performance and reduced the CO2 footprint. The overall process reductions achieved exceed 2.24 million tonnes of CO2 equivalents per year in smelters producing less than 3 million tonnes of aluminum per year.